Understanding Creosote

[Traveler004]

So I've been burning and learning for about 7 fires now. Took a look down my chimney and found it was black all the way down. Very thin layer of black. Stuck my hand down it to feel some black dust and tried to smug it off the side a the vary top to find some flaked off and some was stuck on there to the point of not being able to get it off.

I take it this is an issue after only 7 burns? I should still be shinny silver right?
I'm going to clean it out and start burning with the flue at higher temps.

I think i was closing the primary intake too soon. and leaving it closed after the hottest part of the burn when the embers are just cursing. So now I open the air up and finish off those embers faster and hotter.

 

[Grizzerbear]

The coals wont gunk up your chimney as all the creosote forming properties have been spent. Coaling stage is the cleanest part of a burn. Have you tested the moisture of the firewood.

 

[Traveler004]

The coals wont gunk up your chimney as all the creosote forming properties have been spent. Coaling stage is the cleanest part of a burn. Have you tested the moisture of the firewood.

I'm using super dry eco hardwood. So that's not the issue. I guess i'm just closing primary air too soon. It doesn't look like it's smouldering. It looks like a nice slow burn.

 

[bholler]

I'm using super dry eco hardwood. So that's not the issue. I guess i'm just closing primary air too soon. It doesn't look like it's smouldering. It looks like a nice slow burn.

What temps are you running at with what stove

 

[Traveler004]

The top of the stove is like 250 - 280. I can't get it up to 300 without it looking very wrong. The flue temp i can get to 150. Says optimal on my thermometer and then i cut off the primary and just use secondary but then the temp drops back to 100.

 

[begreen]

What is the flue setup from stove to chimney cap?

 

[Traveler004]

What is the flue setup from stove to chimney cap?

Though the wall and up in into -10 C cold winds. I ignored everyones advice to go though the house because i thought going through the wall would be easy and am now paying for it. (and it turned out to be harder) Now, I'm building a green house against the house protect the chimney from the cold. I also wanted the green house there so in the end it will all work out.

 

[RandyBoBandy]

The top of the stove is like 250 - 280. I can't get it up to 300 without it looking very wrong. The flue temp i can get to 150. Says optimal on my thermometer and then i cut off the primary and just use secondary but then the temp drops back to 100.

Are these Celsius readings? If so I would think you are in the ballpark for proper temps.

 

[Traveler004]

Are these Celsius readings? If so I would think you are in the ballpark for proper temps.

Yes Celsius. Ok cool. It must just be because the chimney is outside and it's very cold up here. Maybe i will just need to clean it very often.

 

[begreen]

The top of the stove is like 250 - 280 (482-496F). I can't get it up to 300 (572F) without it looking very wrong. The flue temp i can get to 150 (302F). Says optimal on my thermometer and then i cut off the primary and just use secondary but then the temp drops back to 100 (212F).

The cold flue explains part of the issue. the stove is also running a bit cool.

300ºC (572F) on the stovetop is a more normal running temp. What starts "looking very wrong"? Are the stovepipe temps, surface reading or probe thermometer?

 

[Chimney Smoke]

Through the wall and up can cause problems but it doesn't have to. I have the same setup with 18 feet of exposed class a chimney after the wall penetration. I burn 2-4 year seasoned wood and I burn it on the warm side, my chimney has no creosote. I get maybe 2 cups of powder soot after burning 3-4 cord each winter. I think the problem you have is too cool stove and flue temperatures either driven by wet wood and/or closing the air too much. And also - no chimney is going to stay shiny silver there will at least be soot in it.

 

[jetsam]

To the original topic, creosote is organic compounds in the wood that have escaped combustion (twice in modern stoves).

It will condense on any surface cooler than 250°F. You can prevent it accumulating in your flue by having more complete combustion (burn hotter, get a more efficient stove), and more importantly by keeping the coldest part (the top) of your flue above 250°F.

You can raise flue temperatures by burning drier wood, burning hotter, and having an insulated flue.

Sweep your flue often at first so you can learn if you have a problem or not.

 

[RandyBoBandy]

Was it ever determined if the class A is double wall insulated or triple wall? Am I correct in my thinking that double wall chimney pipe is better for keeping the exhaust hotter?

 

[blacktail]

I should still be shinny silver right?

No.

 

[Traveler004]

Ok, thanks for all your insights. I think I get it. I will clean often and just keep learning safely. It's so counter to how everything else works. To be safe for other things you usually start lighter and slowly work up. Going light here is what causes the issues. I have to admit having a raging fire in my home still makes me nervous however much I love it.

 

[Traveler004]

The cold flue explains part of the issue. the stove is also running a bit cool.

300ºC (572F) on the stovetop is a more normal running temp. What starts "looking very wrong"? Are the stovepipe temps, surface reading or probe thermometer?

I contacted the manufactures because I found it hard to get the stove top that hot while respecting the 3 eco log rule. Apparently, as i'm told it's normal for these logs. It's a small box also. "Looking very wrong" is a raging fire like I've not seen others do. Ei. flames are not suppose to be licking the glass. I've seen alot of fire boxes and I grew up with a fire place so I kinda know what it's suppose to look like. I don't know how to describe it. I can just tell when it's too much. Anyhow, I got it up to temp by keeping the primary air open for almost the whole first burn. Another thing manual was vague on. "Don't leave the primary air open for extended periods of time." which means what exactly. Not for more then 30 mins or 3 hours, not for more then 3 logs, not more then 300/572 degrees on top. What the heck is extended period of time mean. It means nothing without the missing context.

 

[blacktail]

"Don't leave the primary air open for extended periods of time." which means what exactly. Not for more then 30 mins or 3 hours, not for more then 3 logs, not more then 300/572 degrees on top. What the heck is extended period of time mean. It means nothing without the missing context.

Don't leave it open beyond the initial startup phase of the burn on a new load of wood.

 

[Traveler004]

Don't leave it open beyond the initial startup phase of the burn on a new load of wood.

When is the initial start up phase on the first load of wood finished?

 

[Eightball1313]

When is the initial start up phase on the first load of wood finished?

I have an older pre epa stove, i basically let it roar for 15-20 minutes til i get temps like 400-450 degrees F on the outside of single wall pipe with IR thermometer. usually around 15 minutes or so ill turn the damper to half way and then adjust the air control knobs to gradually bring the flue temps down to say around 350-380 degrees F, then cut air down some more and almost close the damper leaving it like one quarter open and hold a steady 320-340 degree F flue temp through the burn and stove top temp of like 600-650 degree F. once your wood is burned up and is just coals it doesnt matter if the flue temp drops like people said its not making creosote at that time.

So id say the end of the initial startup is when you know you have the wood going good and you know your flue temp is pretty high, so basically for me its when i hit 400-450 flu temp and then i adjust damper and so forth like i explained above.

 

[EbS-P]

I consider my startup phase over when more most more( than half) of the load is flaming.

I think the Fact that burning wide open was the only way to get to 300c tells me your fuel load is too small or you don’t have enough draft. the stove top temps actually go up once you close the air down on a hot fire. Just keep trying new things. Try 4 logs. Try cracking a window. Try getting to stove hot and turn the air way down and see what happens. I know with my stove now (didn’t have a clue about this the first month I was running it) that it behaves differently based on how deep the coal bed is. Just few coals and I have to turn it down in stages on deep hot bed of
Coals once the stove top is back up to 200C I can turn it all the way down and walk away. On a cold stove it’s too unpredictable to say this is how I always run it.

Evan

 

[blacktail]

When is the initial start up phase on the first load of wood finished?

I guess it's kind of hard to give a specific description. I'd say it's when the fire appears strong or when most of the wood has caught fire. Or...once she gets a' rippin!
It could be 15 minutes after a cold start or 3 minutes after doing a hot reload.

 

[Traveler004]

I had a pretty good burn i think. I started with 4 logs and let it rip with the door closed but not tight and breaking them up as soon as i could. This seemed to work to get it up to temp. Then i loaded 3 logs and closed it up just fiddled with the primary air keeping the flue hot enough. By the 3rd load i put in 3 log and was able to just leave it on 2ndary air. The 4th load i just used 2 logs on a full hot bed of coals. The temp stayed up. So yeah, there is no single recipe. Too many variables but i'm definitely getting a feel for it.